The present invention relates to a power control device for controlling power supply to household electrical appliances, a remote control receiving device for receiving a remote control optical signal from a remote control device, and an optical communications device for performing optical communications.
Conventionally, there is known a remote control receiving device which is mounted on general household electrical appliances for implementing ON/OFF (operating/standby) control of power supply circuits thereof.
FIG. 6 is a schematic configuration diagram showing main part of an household electrical appliance using the above-stated remote control receiving device. On the primary side of a power supply transformer 7, there are provided a rectifying and smoothing circuit 5 and a primary regulator 6. The rectifying and smoothing circuit 5 composed of a rectifying circuit 3 and a smoothing capacitor 4 and connected to an AC (alternating current) 100V commercial power source 1 via a solid-state relay (SSR) 2. On the secondary side of the power supply transformer 7, there are provided a first rectifying and smoothing circuit composed of a diode 10 and a capacitor 11, and a second rectifying and smoothing circuit composed of a diode 12 and a capacitor 13. An output from the first rectifying and smoothing circuit is connected to an input terminal of a photocoupler 9, and an output terminal of the photocoupler 9 is connected to the primary regulator 6. A low power-loss voltage regulator 8 is used on the output side of the second rectifying and smoothing circuit so as to supply power at a stable power supply voltage. The solid-state relay 2, the rectifying and smoothing circuit 5, the primary regulator 6, the power supply transformer 7, the low power-loss voltage regulator 8, the photocoupler 9, the diode 10, the capacitor 11, the diode 12, and the capacitor 13 constitute a main power circuit 20. Further, a standby power supply transformer 109, a rectifying and smoothing circuit 110, and a low power-loss voltage regulator 111 constitute an auxiliary power supply circuit 112, while a remote control light receiving unit 113 and a microcomputer 114 constitute a remote control light receiving circuit 115.
As shown in FIG. 6, in a household electrical appliance which uses the above-stated remote control receiving device, the auxiliary power supply circuit 112 supplies power to the remote control light receiving circuit 115 during standby. In the standby state, the solid-state relay 2 is in an OFF state, where power supply to the main power circuit 20 is shut off.
When a user attempts to turn on power of an apparatus by remote control, the remote control light receiving unit 113 receives an optical signal transmitted from a remote control transmitting device. Upon receiving an electric signal from the remote control light receiving unit 113, the microcomputer 114 outputs a control signal to the solid-state relay 2 to set the solid-state relay 2 to an ON state. This makes the main power circuit 20 connected to the commercial power source 1 supply power to each part of the circuit and put the household electrical appliance into an operating state.
On the other hand, when a user attempts to stop the household electrical appliance in operation, the remote control light receiving unit 113 also receives an optical signal transmitted from the remote control transmitting device. Upon receiving an electric signal requesting stop of operation detected by the remote control light receiving unit 113, the microcomputer 114 outputs a control signal to the solid-state relay 2 so as to set the solid-state relay 2 to an OFF state. Consequently, a power supply line between the main power circuit 20 and the commercial power source 1 is intercepted, which brings the household electrical appliance into a stopped state i.e. a standby state. In the standby state, the auxiliary power supply circuit 112 supplies power to keep the microcomputer 114 and the remote control light receiving circuit 115 in operation, resulting in continuous consumption of power though small in amount.
There is another remote control receiving device, which is mounted on general household electrical appliances to implement ON/OFF (operating/standby) control of power circuits thereof. In this device, a high-capacity capacitor charged during operation is used as an auxiliary power source during standby.
FIG. 7 is a schematic configuration diagram showing main part of an household electrical appliance using the above-stated remote control receiving device. This remote control receiving device uses a high-capacity capacitor 122, for example a high-capacity electrolytic capacitor or a super capacitor, as an auxiliary power source of a remote control light receiving circuit 215 instead of the auxiliary power supply circuit 112 shown in FIG. 6. The high-capacity capacitor 122 is connected to an output of the low power-loss voltage regulator 8 via a diode 121.
The remote control light receiving circuit 215 made up of a microcomputer 214 and a remote control light receiving unit 213 shown in FIG. 7 receives an optical signal transmitted from the remote control transmitting device even during standby like the case of FIG. 6. Therefore, the remote control light receiving circuit 215 requires continuous operation. During operation, the remote control light receiving circuit 215 is supplied with power from a DC power supply line 14 of the main power circuit 20, while the high-capacity capacitor 122 is simultaneously charged via the DC power supply line 14 and the diode 121.
In the above-stated remote control receiving device, when a user attempts to stop operation of the in household electrical appliance by remote control, the remote control light receiving unit 213 receives the instruction as an optical signal from the remote control transmitting device in the same way as that of FIG. 6. The microcomputer 214 determines the contents thereof and outputs a control signal to the solid-state relay 2 to set the solid-state relay 2 to an OFF state. After the solid-state relay 2 is in the OFF state, a voltage of the DC power supply line 14 becomes zero, and so the high-capacity capacitor 122 starts discharging power. Thus, the high-capacity capacitor 122 is used as a power source of the remote control light receiving circuit 215.
When a standby time is longer, the high-capacity capacitor 122 runs short of a charged power. To cope with this problem, the microcomputer 214 monitors a voltage supplied by the high-capacity capacitor 122. When the voltage becomes less than a certain voltage level, the microcomputer 214 outputs a control signal to the solid-state relay 2 to set the solid-state relay 2 to an ON state for recharging the high-capacity capacitor 122. Upon completion of recharge of the high-capacity capacitor 122, the microcomputer 214 outputs a control signal to the solid-state relay 2 to set the solid-state relay 2 again to an OFF state. In this way, ON/OFF operation of the main power circuit 20 is regularly repeated, which causes consumption of power on the same basis.
As an optical communications device, there is a portable device implementing two-way communications. The optical communications device incorporates a battery 151 and uses it as a power source as shown in FIG. 8. In the optical communications device implementing two-way communications, one LED executes both transmitting and receiving operations.
A CPU (Central Processing Unit) 153 mounted on the optical communications device 150 is connected via a signal bus 154 to a ROM (Read Only Memory) 155 storing programs necessary for operating the CPU 153, a RAM (Random Access Memory) 156 for use in storing transmitted and received data, and a UART (Universal Asynchronous Receiver Transmitter) 157 for conducting Serial/Parallel conversion. An output of the UART 157 is connected in sequence to a modulator 158 for modulating serial data outputted from the UART 157, a driving circuit 159 for driving an LED 160, and the LED 160 for sending an optical signal Lr1. The LED 160 converts an optical signal Lr2 received as a light receiving element to an electric signal. An output of the LED 160 is connected in sequence an amplifier 161 for amplifying the output, and a demodulator 162 for demodulating a signal outputted from the amplifier 161 and converting it to a serial data signal. An output of the demodulator 162 is connected to an input terminal of the UART 157. Function blocks of the CPU 153, the ROM 155, the RAM 156, the UART 157, the modulator 158, and the demodulator 162 are formed on one LSI chip 171.
In the above-configured optical communications device 150, an optical signal Lr1 transmitted from the LED 160 is received by an optical communications device 170 having the same function as the optical communications device 150. On the other hand, an optical signal Lr2 transmitted from the optical communications device 170 is received by the LED 160 of the optical communications device 150. In this way, two-way communications with optical signals are implemented between the optical communications device 150 and the optical communications device 170. It is noted that the LED 160 is used in a transmission (light emission) mode and a reception (light reception) mode, and switching therebetween is made with use of a Tx/Rx switch 163. The switching operation of the Tx/Rx switch 163 is controlled by the CPU 153.
However, the remote control receiving devices shown in FIGS. 6 and 7 need to retain the microcomputers 114 and 214 as well as the remote control light receiving units 113 and 213 in an operating state even when the apparatus is on standby in order to receive and execute a next instruction from a remote control transmitting device and the like. This causes continuous consumption of power during standby.
In addition, as to the optical communications devices 150 and 170 using the battery 151 as a power source shown in FIG. 8, after completing a communication and entering into a standby state, it is impossible to predict when the optical communications devices 150 and 170 receive a next optical signal from a communicating counterpart and restart operation. Accordingly, the optical communications devices 150 and 170 need to be in a reception acceptable state all the time. More particularly, the optical communications devices 150 and 170 need to keep a partial function of the CPU 153 and the entire function of a remote control light receiving unit 172 running even during standby, which causes continuous consumption of the battery 151.
In the case of household electrical appliances in particular, a period of time in a standby state is longer than a period of time actually in use. Therefore, decrease of power consumption during standby is an object common to all household electrical appliances.
It is an object of the present invention to provide a power control device, a remote control receiving device, and an optical communications device, which can make virtually zero power consumption during standby and remarkably improves life time of a battery.
In order to accomplish the above-stated object, a first aspect of the present invention provides a power control device to be mounted on an apparatus, comprising: a switch circuit connected between a power supplied circuit of the apparatus and a power source and brought into an OFF state when the apparatus turns into a standby state; and an LED outputting an electric signal in an unbias condition to bring the switch circuit into an ON state when the LED detects an optical signal.
According to the above configured power control device, the switch circuit connected between the power source and the power supplied circuit is brought into an OFF state when the apparatus turns to a standby state. On standby, if the LED in an unbias condition receives an optical signal, that is, a ray of light having a wavelength within a sensitivity range of the LED from the outside, the LED generates electromotive force, and outputs an electric signal to bring the switch circuit into the ON state. When the switch circuit is in the ON state, power is supplied to the power supplied circuit, and the apparatus is brought into an operating state. Since the switch circuit electrically intercepts the power supplied circuit when the apparatus is on standby, power consumption thereof can be virtually zero during standby. When a battery is used for a power source of the portable apparatus in particular, the switch circuit, which intercepts the power supplied circuit from the battery during standby, results in remarkable improvement of battery consumption.
In one embodiment of the first aspect of the present invention, the power control device further comprises retaining means for retaining the switch circuit in the ON state after the electric signal from the LED brings the switch circuit into the ON state.
According to the power control device in the above embodiment, once the electric signal from the LED brings the switch circuit into the ON state, the ON state thereof can be retained even if the LED does not receive an optical signal thereafter.
A second aspect of the present invention provides a remote control receiving device mounted on an apparatus, comprising: a switch circuit connected between a power supplied circuit of the apparatus and a power source and brought into an OFF state when the apparatus turns into a standby state; and an LED as a light receiving element that receives an optical signal for remote control from a transmitting device, and outputs an electric signal in an unbias condition to bring the switch circuit into an ON state when the LED detects the optical signal.
According to the above-configured remote control receiving device, in addition to the effects described in the first aspect of the present invention, the LED used for driving the switch circuit makes it possible to simplify the circuit configuration and decrease a cost.
A third aspect of the present invention provides an optical communications device, comprising: a switch circuit connected between a power supplied circuit of the optical communications device and a power source and brought into an OFF state when the optical communications device turns to a standby state; and an LED as a light receiving element that receives an optical signal from a transmitting device, and outputs an electric signal in an unbias condition to bring the switch circuit into an ON state when the LED detects the optical signal.
According to the above-configured optical communications device, in addition to the effects described in the first aspect of the present invention, the optical communications device can implement both two-way optical communications and one-way optical communications. In the case of the one-way optical communications, the present invention is applied to a receiving side of the optical communications device.